1. Field of the Invention
The present invention relates to an apparatus, a system and a method for reading an image borne on a support by a manual operation of an operator, and also relates to a computer-readable recording medium in which an image reading program for realizing the apparatus, the system and the method is recorded. The present invention is particularly useful when applied to a hand-held scanner that reads an image as an operator moves it with respect to a support.
2. Description of the Related Art
In general, scanners that read images borne on supports by scanning the supports are grouped into two types: one type is exemplified by a flatbed scanner and a sheet-fed scanner that reads the image by automatically scanning the support set/fed in the scanner; and the other type is exemplified by a hand-held scanner that reads image by manually scanning the support, namely, as the scanner is moved by operator's hand.
A typical hand-held scanner comprises a scanner unit and a data processing unit. The scanner unit reads an image borne on a support by an operator's manual operation of the scanner unit with respect to the support, and the data processing unit processes the data of the image that has been read by the scanner unit. Specifically, a line sensor in the scanner unit reads the image line by line and detects an amount of relative movement of the scanner unit with respect to the support, whereupon the data processing unit transfers the image data, each data piece being a line of the read image, to information processing equipment, e.g., a computer, installed downstream of the data processing unit in accordance with the detected amount of relative movement of the scanner unit.
Upon receipt of the image data, the information processing equipment restores the read image by fitting all the image data pieces together, each image data piece in a line, thereby generating the two-dimensional image.
Moving the scanner unit on a support by operator's hand causes the hand-held scanner to read an image on the support. If rapid movement (scanning) of the scanner unit by operator's hand makes a cycle of pulse signals for detection of amount of movement of the scanner unit shorter than the cycle of a driving signal of the data processing unit, the image data that is to be transferred to the information processing equipment would skip or fail to pick up data pieces of part of the image. As a result, the image finally restored by the information processing equipment would be short in size in the scanning direction.
As a solution, Japanese Patent Laid-Open (Kokai) publication No. 2000-349984 proposed an image reading apparatus that is equipped with a image data generating section for generating image data in accordance with the scanner unit's amount of movement detected by a rotary encoder (an amount-of-movement detecting section). With this known image reading apparatus, even if the scanner unit is rapidly moved (to scan an image) by operator's hand so as to make a cycle of pulse signals for detection of amount of movement of the scanner unit shorter than the cycle of a driving signal of the data processing unit, the missing portion of the image due to the skipped scanning will be compensated by making one or more copies of the preceding image portion which is contained in the image data and which has been read immediately before the missing portion. Thereby it is possible to reproduce the image without shortage in size in the scanning direction regardless of the scanning speed.
Assuming that an image reading apparatus reads an image with high resolution, an increased amount of data is obtained by the line sensor by the scanner unit, as image data, each data piece corresponding to a line of the image. So the image reading apparatus transfers such an increased amount of data to the information processing equipment to restore the image. For this data transfer, the image reading apparatus requires a high-speed communication interface (hereinafter also called I/F),or a buffer, for temporarily storing data to be transferred to the information processing equipment.
But a high-speed communication I/F is expensive, causing an increase of price of the image reading apparatus. Further, to read an image with a higher resolution needs a larger-capacity buffer, which also would cause an increase of the manufacturing cost of the image reading apparatus.
If the amount of data the image reading apparatus transfers to the information processing apparatus were small, the image reading apparatus not only could have been manufactured with a reasonable cost but also would have guaranteed sure transfer of data.